WO1989009540A1

WO1989009540A1 - A suspension arrangement for a spray boom

Info

Publication number: WO1989009540A1
Application number: PCT/DK1989/000072
Authority: WO
Inventors: Dan Rosenbaek
Original assignee: Dems Engineering I/S
Priority date: 1988-04-07
Filing date: 1989-04-04
Publication date: 1989-10-19
Also published as: DK188788D0; AU3444889A; DK188788A

Abstract

In a "centre-homing" suspension arrangement with a quadrangle linkage (4, 5, 8, 9) for a spray boom (1) for spraying a field (2), the new feature consists in that the quadrangle linkage constitutes a parallelogram, and that the "centre-homing" function is provided by elastically functioning return mechanisms (15, 16), e.g.in the form of air cylinders (18) with closed chambers (19, 20) on both sides of the piston (17). With this arrangement it is achieved that the spray boom (1), when moving transversely to the direction of forward motion - e.g. towards the right or the left in the drawing - does not alter its orientation relative to the field (2). The angle between the spray boom (1) and the field (2) may be adjusted, and its height above the field (2) changed, by raising or lowering upwardly and downwardly adjustable members (10, 11), in which the suspension rods (6, 7) for the boom (1) are suspended.

Description

A suspension arrangement for a spray boom.

TECHNICAL FIELD

The present invention relates to a suspension arrange¬ ment for a spray boom, said arrangement being of the kind set forth in detail in the preamble of claim 1.

BACKGROUND ART

In previously known suspension arrangements of the kind referred to, the force with which the spray boom is urged back to the normal position or mid-position from a position away therefrom, is provided by con¬ structing the quadrangle linkage in the form of a trapezium, so that the weight of the spray boom itself provides the requisite return force through the quadrangle linkage. As far as the return function as such goes, such a suspension arrangement is, of course, extremely reliable, being based on the force of gravity, but at the same time it is the cause of a disadvantage being serious in many cases, in that the angular position of the spray boom is varied during movement away from the normal position or mid-position and back to this position. Apart from causing varia¬ tions in the spraying of the liquid, which may be disadvantageous in certain cases, this known arrange¬ ment makes it necessary for the return force not only to overcome the purely transl ational inertia of the spray boom, but also to a certain extent to overcome its rotational moment of inertia about an axis extend¬ ing in the direction of forward movement. This again means that the return to the normal position or mid- position may be considerably slower than in the case of a simple translatory movement.

DISCLOSURE OF THE INVENTION It is the object of the present invention to provide a suspension arrangement of the kind initially referred to, that does not suffer from the disadvantages re¬ ferred to above and with which the return movement takes a minimum of time, and this object is achieved with a suspension arrangement, according to the pre¬ sent invention also exhibiting the features set forth in the characterizing clause of claim 1. By using a parallelogram as the quadrangle linkage a practically pure translational movement of the spray boom is achieved, and the return force, which in the previous¬ ly known suspensions was provided by the use of a trapezium-shaped quadrangle linkage, is provided by means of special elastically functioning return mecha¬ nisms, that may easily be constructed in such a man- ner, that they may be adapted to the conditions in each case.

Suitable embodiments of the suspension arrangement according to the present invention, the effects of which are explained in the following detailed portion of the present specification, are set forth in claims 2 to 9.

BRIEF DESCRIPTION OF THE DRAWING

In the following detailed portion of the present spe¬ cification the present invention will be explained in more detail with reference to an exemplary embodiment of a suspension arrangement for a spray boom, said arrangement being shown on the drawing in a partly highly diagrammatic manner, Figure 1 showing a tractor, on which a spray boom is suspended by means of a suspension arrange¬ ment according to the present invention,

Figure 2 is a slightly enlarged portion of Figure 1 showing the parallel displacement of the spray boom, and

Figure 3 is also a slightly enlarged portion of Fi¬ gure 1 showing how the spray boom may be inclined relative to the tractor.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The spray boom 1 shown in the drawing, being in a known manner (not shown) provided with nozzles for spraying a liquid across a field 2, is suspended on a tractor 3 by means of a parallelogram linkage.

The lower linkage rod in the parallelogram likage, being shown in Figures 1 and 2 as extending substan¬ tially parallel to the field 2, is constituted by that portion of the spray boom 1 lying between a lower left-hand linkage corner 4 and a lower right-hand linkage corner 5, and is connected to an upper left- hand linkage corner 8 and an upper right-hand linkage corner 9 through a left-hand suspension rod 6 and a right-hand suspension rod 7 respectively.

In the exemplary embodiment shown the upperleft-hand and right-hand linkage corners 8 and 9 respectively are situated on one end of a cantilever 10 and 11 respectively, the opposite end of which is secured to the piston rod in a hydraulic piston-cylinder unit 12 and 13 respectively.

The piston-cylinder units 12 and 13 are secured to the tractor 3 through a diagrammatically outlined support¬ ing unit 14, which in a manner known per se may be adapted to be secured in a releasable manner to suitable coupling members on the tractor 3.

The piston-cylinder units 12 and 13 are connected to the hydraulic system of the tractor through conduits and operating means, e.g. manually operable valves, in such a manner that by operating said operating means in a suitable manner it is possible to raise or lower the cantilevers 10 and 11 and thus raise or lower the lower left-hand and right-hand linkage corners 4 and 5 respectively situated on the spray boom 1 and thus adjust the latter as desired in various heights and/or angular positions in relation to the field 2.

During forward movement of the tractor 3 the spray boom 1 is influenced in directions transverse to the direction of motion - e.g. in the longitudinal direc¬ tion of the boom - by various forces seeking to move the boom 1 away from the "normal" mid-position shown in Figure 1.

The forces referred to may be due to bumps in the field 2 being propagated through the tractor 3 to the boom 1, or encounters with plants or trees;further, during work on an inclined field there will be a component of the force of gravity on the spray boom seeking to move the boom transversely to the direction of motion.

It is, of course, necessary to prevent said trans¬ versely acting influences in moving the spray boom 1 to such an extent, that its proper functioning is affected or its connection to the tractor 3, compriε- ing inter alia the connection conduits to the spray nozzles, is affected or interrupted. On the other hand, the suspension of the spray boom 1 should not be so rigid, that the suspension arrangement can be de¬ stroyed or at least deformed by reaction forces. With a view to counteracting said forces to a moderate extent the suspension arrangement comprises a pair of elastically acting return mechanisms in the form of piston-cylinder units 15 and 16, the pistons 17 of which divide each cylinder 18 forming two closed cy¬ linder chambers 19 and 20.

In the exemplary embodiment shown the cylinder end of each piston-c linder unit 15 and 16 is linked to an upright 21 and 22 respectively being rigidly secured to the spray boom 1, and with their piston ends said units are linked to a linkage point 23 and 24 respec¬ tively on the left-hand and right-hand suspension rod 16 and 17 respectively at a distance above the lower left-hand linkage corner 4 and the lower right-hand linkage corner 5 respectively.

If as indicated in dotted lines in Figure 2 the spray boom 1 is displaced through a short distance towards the left, the volume of the cylinder chambers 19 to the left of the pistons 17 will be increased, whilst the volume of the cylinder chambers 20 to the right of the pistons 17 will be decreased. This will cause the pressure to fall in the cylinder chambers 19 and to rise in the cylinder chambers 20, and the resultant force thus produced on the pistons 17 will seek to counteract the movement, i.e. seek to bring the spray boom 1 back to the mid-position drawn in full lines.

The force, with which the pistons 17 tend to move the spray boom 1 back to the mid-position, depends on the pressure in the cylinder chambers 19 and 20 being preferably filled with air, and the "spring characte¬ ristic" may thus be easily changed by changing the pressure in the cylinder chambers. This can suitably be achieved by equipping the cylinder chambers with suitable connection means, such as a valve of the same kind used on the wheels of the tractor for filling its tyres with air. In order to simplify the procedure with filling air into or letting air out of the cylin¬ der chambers, cylinder chambers fuctioning in a mutu¬ ally analogous manner may by connected to each other through suitable pressure conduits 25 and 26, each provided with a valve 27 and 28 respectively of the kind referred to. If the tractor is permanently pro¬ vided with a compressor, the pressure conduits 25 and 26 may, of course, be suitably connected to the com¬ pressor, e.g. using requisite valves and pressure gauges.

As will easily be seen when looking at Figure 2, a movement of the spray boom 1 in a direction opposite to the one referred to will, due to the symmetrical construction, be counteracted by a likewise oppositely directed return force, being produced in a manner fully analogous to the return force referred to above.

Figure 3 shows how the spray boom 1 may be inclined relative to the field 2, in the example shown by raising the right-hand cantilever 11, the left-hand cantilever 10 remaining in its original position. Admittedly, when the spray boom 1 is inclined in this manner, the quadrangle linkage comprising the corners 4, 5, 8 and 9 is no longer a "pure" parallelogram, since the raising of the upper right-hand linkage corner 9 by means of the right-hand hydraulic piston- cylinder unit 13 causes an extension of the distance between the upper linkage corners 8 and 9, but within the normally occurring variations of the angular posi¬ tion of the spray boom 1 this increase in the distance is so small, that it may be ignored in practice. Thus, the effect of e.g. the elastically functioning return mechanisms in the form of the piston-cylinder units 15 and 16 as explained with reference to Figure 2 will be practically unchanged.

It is, of course, also possible in a manner not shown to raise the spray boom 1 as a whole, possily also in a inclined position, by raising both cantilevers 10 and 11 to a suitable extent.

The extreme end portions 29 and 30 of the spray boom 1 are hingedly connected to the remainder of the spray boom through hinges 31 and 32 respectively in such a manner, that they can give way in a rearward direc¬ tion, e.g. when colliding with a tree 33. After having passed the obstruction, the end portion in question is returned to the working position shown by means of a rotational actuator 34 or 35 respectively, said actua¬ tor being adapted to exert a permanent forward turning moment on the end portions 29 and 30 respectively. The rotational actuators 34 and 35 may suitably be consti¬ tuted by fluid pressure motors being permanently con¬ nected to a source of fluid pressure sufficiently low for the end portions in question to give way, and sufficiently high to return them to the working posi- tion.

Closer to its middle portion, the spray boom 1 may also be provided with hinges 36 and 37 and suitable rotational actuators 38 and 39, primarily with a view to making it possible to run the tractor 3 between the various fields without having to dismantle the suspen¬ sion arrangement. If the hinges 36 and 37 and the rotational actuators 38 and 39 are adapted to function in substantially the same manner as the hinges 31 and 32 and the rotational actuators 34 and 35 placed at the extreme ends of the spray boom, further protection of the latter may be achieved, e.g. when moving the boom in a low position across a field with tall plants, between which there may be hidden poles or the like.

In the exemplary embodiment shown, the linkage points 23 and 24, where the piston-cylinder units 15 and 16 respectively are linked to the suspension rods 6 and 7 respectively, are situated between the linkage corners 4 and 8 and linkage corners 5 and 9 respectively. It is, however, possible within the scope of the present invention to place these linkage points in other posi¬ tions, e.g. on the end of a downwardly directed exten- sion of each suspension rod 6 and 7 respectively. It also lies within the scope of the invention to place the elastically functioning return mechanisms in an¬ other manner than the one shown and referred to, as they may e.g. be adapted to connect the spray boom 1 directly to the supporting unit 14; if so, care should be taken that their functioning is not substantially affected by the spray boom possibly being raised, lowered and/or placed in an inclined position.

In the example shown, the suspension arrangement is adapted to be secured to a tractor, but is lies within the scope of the present invention to construct the suspension arrangement with a view to being secured to vehicles of other types or to integrate the suspension arrangement in a purpose-built vehicle.

Claims

1. A suspension arrangement for a spray boom ( 1 ) , especially for distributing liquid over agricultural areas, said arrangement being of the kind comprising a quadrangle linkage having two (4,5) of its four linkage corners (4,5,6,7) permanently connected to the boom (1) and two (6,7) permanently connected to a vehicle (3), with which the boom during its operation is made to travel substantially transversely to its own longitudinal direction across the area in ques¬ tion, said suspension arrangement further being adapt¬ ed in such a manner, that when the spray boom (1) is positioned away from a normal position or mid-position it is urged toward this position, c h a r a c t e - r i z e din a) that said quadrangle linkage, considered kinemati- cally, substantially has the form of a parallelo¬ gram, and b) that the suspension arrangement comprises elasti- cally functioning return mechanisms (15,16) urging the boom (1) towards said normal position or mid- position.

2. A suspension arrangement according to claim 1, c h a r a c t e r i z e d in that at least one of the two linkage rods (6,7) comprised by the quadrangle linkage connecting the boom (1) to the vehicle (3) with at least one of its ends is connected to a member (10,11) with adjustable height, with which the height of that end (4,5) of said rod being linked to the boom (1) may be adjusted relative to the vehicle.

3. A suspension arrangement according to claim 2, c h a r a c t e r i z e d in that said member (10,11) being adjustable in height comprises a part of a level adjustment mechanism (12,13) being or being adapted to be permanently connected to the vehicle (3).

4. A suspension arrangement according to any one or any of the claims 1 to 3, c h a r a c t e r i z e d in that the two linkage rods (6,7) being comprised by the quadrangle linkage and connecting the boom (1) to the vehicle (3) extend upwardly from the boom (1).

5. A suspension arrangement according to claim 3 or 4, c h a r a c t e r i z e d in that each level adjustment mechanism is constituted by a hydraulic piston-cylinder unit (12,13) being or being adapted to be connected to the hydraulic system of the vehicle (3) through suitable operating means, such as control valves.

6. A suspension arrangement according to any one or any of the claims 1 to 5, c h a r a c t e r i z e d in that the return mechanisms comprise at least one piston-cylinder unit (15,16) with a cylinder (18) being closed at both ends and adapted to be filled with a gas in the cylinder chambers (19,20) situated on both sides of the piston (17).

7. A suspension arrangement according to claim 6, c h a r a c t e r i z e d by means (27,28) to fill the cylinder chambers (19,20) with a gas under super- atmospheric pressure of desired magnitude.

8. A suspension arrangement according to claim 6 or 7, c h a r a c t e r i z e d in a) that the return mechanisms comprise at least two piston-cylinder units (15,16), and b) that both or all piston-cylinder units are fluidi- cally connected (25,26) to each other in such a manner, that those cylinder chambers, the volumes of which during movements of the boom are changed in the same direction, are connected to each other.

9. A suspension arrangement according to any one or any of the claims 1 to 8, c h a r a c t e r i z e d in that the or each return mechanism (15,16) with one of its ends is connected to the boom (1) and with its other end is connected to at least one of those linkage rods (6,7) comprised in the quadrangle linkage connecting the boom (1) to the vehicle (3) in a posi¬ tion (23,24) lying at a distance from the linkage corner (4,5) belonging to the boom.